The broad, long-term objective of this project is to investigate structure-property-design relationships of novel fast-curing biodegradable cement composites for bone replacement and repair. The study of the composites will use synthetic fumarate polyesters and an inorganic filler, calcium sulfate, as major components. The project will include synthesis and characterization of the biodegradable polyesters with variable backbones. This in an attempt to improve our understanding of the effects of polymer structure on the cements' physical properties and degradation. Four specific aims are proposed. Aim 1 proposes studies to expand the range of fumarate polymers via synthesis of polyesters and copolyesters by ester-exchange reaction of diethyl fumarate, propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, and 1,4-cyclohexanedimethanol. Aim 2 proposes to characterize the polyesters with the objective to correlate the microstructure, molecular weight, and polymer backbone flexibility with compressive strength and in vitro degradation of the composites. Aim 3 proposes to carry out curing studies of the cement composites and determine the impact of the structural effects of the polyesters on the cement composites' workability, maximum curing time and temperature. Aim 4 proposes to study in vitro degradation and mechanical properties of the cured cement compositions with an objective to generate and analyze data on the physical and mechanical properties of the cement that are considered germane to its clinical performance as bone repair material.